Slide surface construction

ABSTRACT

A slide surface construction is formed of an aggregate of Ni crystals having a face-centered cubic structure. The aggregate includes {220} oriented Ni crystals with their {220} planes (by Miller indices) oriented toward a slide surface and having a content S in a range represented by S&lt;25%. If the content of the {220 } oriented Ni crystals is set in such a range, a large number of quadrangular Ni crystals are precipitated in the slide surface, so that the oil retention and the initial conformability are improved by the Ni crystals. Thus, the slide surface construction exhibits an excellent seizure resistance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a slide surface constructionconstituting a slide surface for a mating member.

2. Description of the Prior Art

An example of such a conventionally known slide surface construction isa Ni-plated layer which is provided around the outer journal portion ofa base material, for example, in a cam shaft for an internal combustionengine, in order to improve the seizure resistance of the cam shaft.

However, under existing circumstances where high speed and high outputof the internal combustion engine are desired, the prior art slidesurface construction suffer from problems of insufficient oil retainingproperty, i.e., oil retention and poor initial conformability andseizure resistance.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a slide surfaceconstruction of the type described above, which has sufficient oilretention and good initial conformability by specifying the crystalstructure, thereby improving its seizure resistance.

To achieve the above object, according to the present invention, thereis provided a slide surface construction, which is formed of anaggregate of metal crystals having a face-centered cubic structure, theaggregate including (hh0) oriented metal crystals with their (hh0)planes (by Miller indices) oriented toward a slide surface, a content Sof the (hh0) oriented metal crystals being in a range represented byS<25%.

In the aggregate of the metal crystals having the face-centered cubicstructure, if the content S of the (hh0) oriented metal crystals withtheir (hh0) planes (by Miller indices) oriented toward the slide surfaceis set in the above described range, a large number of pyramid-shaped(and/or truncated pyramid-shaped) metal crystals are precipitated in theslide surface into a mutually biting state. As a result, the slidesurface takes on an intricate morphology comprising a large number ofcrests, a large number of valleys formed between the crests, and a largenumber of swamps formed due to the mutual biting of the crests.Therefore, the slide surface construction has good oil retention. Inaddition, the initial conformability of the slide surface constructionis enhanced by the preferential wearing of the tip ends of thepyramid-shaped metal crystals. The seizure resistance of the slidesurface construction can be improved by such oil retention and initialconformability. However, if the content S of the (hh0) oriented metalcrystals is equal to or more than 25%, the morphology of the slidesurface tends to be simplified with an increase in content of the (hh0)oriented metal crystals and hence, the oil retention and the initialconformability of the slide surface construction are reduced.

The above and other objects, features and advantages of the inventionwill become apparent from the following description of a preferredembodiment, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an essential portion of a cam shaft;

FIG. 2 is a sectional view of an essential portion of a journal portionin the cam shaft;

FIG. 3 is a perspective view illustrating a face-centered cubicstructure and its (hh0) plane;

FIG. 4 is a perspective view of an essential portion of one example of aslide surface construction;

FIG. 5 is a sectional view taken along line 5--5 in FIG. 4;

FIG. 6 is an X-ray diffraction pattern for one example of the slidesurface construction;

FIG. 7 is a photomicrograph showing the crystal structure of the slidesurface in one example of the slide surface construction;

FIG. 8 is an X-ray diffraction pattern for another example of the slidesurface construction;

FIG. 9A is a photomicrograph showing the crystal structure of the slidesurface in the other example of the slide surface construction;

FIG. 9B is an enlarged photomicrograph taken from FIG. 9A;

FIG. 10 is a graph illustrating results of a seizure test;

FIG. 11 is a plan view illustrating the crystal plane located on eachslant in one example of a quadrangular pyramid-shaped tip end portion;and

FIG. 12 is a plan view illustrating the crystal plane located on eachslant in another example of a quadrangular pyramid-shaped tip endportion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, a cam shaft 1 for an internal combustionengine includes a base material 2 of cast iron. A lamellar slide surfaceconstruction 4 is formed by plating around the outer peripheral surfaceof a journal portion 3 of the base material 2.

As shown in FIGS. 3 and 4, the slide surface construction 4 is formed ofan aggregate of metal crystals having a face-centered cubic structure(fcc structure). The aggregate includes (hh0) oriented metal crystalswith their (hh0) planes (by Miller indices) oriented toward a slidesurface 4a for a bearing member 5. The content S of the (hh0) orientedmetal crystals is set in a range represented by S<25%.

If the content S of the (hh0) oriented metal crystals 6 is set in theabove range, a large number of pyramid-shaped (and/or truncatedpyramid-shaped), e.g., quadrangular pyramid-shaped (in the illustratedembodiment) metal crystals 6 are precipitated in the slide surface 4ainto mutually biting states. Thus, the slide surface 4a takes on anintricate morphology comprising a large number of crests 7, valleys 8formed between the crests 7, and a large number of swamps 9 formed dueto the mutual biting of the crests 7. Therefore, the slide surfaceconstruction 4 has a good oil retention. In addition, the tip ends ofthe quadrangular pyramid-shaped metal crystals 6 are preferentiallyworn, thereby providing an improved conformability to the slide surfaceconstruction 4.

Examples of metals having the fcc structure are those of simple metalsuch as Pb, Ni, Cu, Pt, Al, Ag, Au, etc., and alloys thereof.

In the plating treatment for forming the slide surface construction 4according to the present invention, basic conditions for theelectrolytic deposition of a Ni-plating are as given in Tables 1 and 2.

                  TABLE 1    ______________________________________    Plating bath composition (g/liter)    Nickel sulfate                  Nickel chloride                              Boric acid    ______________________________________    200˜400 50˜150                              5˜50    ______________________________________

                  TABLE 2    ______________________________________    Treating conditions    Plating Plating bath temperature                            Cathode current density    bath pH (°C.)    (A/dm.sup.2)    ______________________________________    3˜6            10˜70     7˜12    ______________________________________

In the electrolytic deposition of the Ni-plating under theabove-described conditions, the precipitation and content of the (hh0)oriented Ni crystals are controlled by the cathode current density, thepH of the plating bath and the like.

In addition to electrolytic plating processes, examples of other platingtreatments that may be used are PVD processes, CVD processes, sputteringprocesses, ion plating and the like, which are gas-phase processes.Conditions for Pt- or Al-plating by a sputtering process are, forexample, an Ar pressure of 0.8 to 1 Pa; an Ar acceleration power of 200to 1,000 W in direct current; and a base material temperature of 80° to300° C. Conditions for Al-plating by a CVD process are, for example,using a starting material of Al (CH₃)₃ ; a gas flow rate of 1 to 10cc/min.; a pressure of 50 to 300 Pa within the chamber; and a basematerial temperature of 300° to 600° C.

Particular examples will be described below.

A plurality of cam shafts 1 for internal combustion engines wereproduced by subjecting the outer peripheral surface of a journal portion3 of a base material of cast iron to an electrolytic Ni-plating processto form a slide surface construction 4 comprised of an aggregate of Nicrystals.

Tables 3 and 4 show the conditions used for the electrolytic depositionof the Ni-plating in examples 1 to 11 of the slide surface construction4.

                  TABLE 3    ______________________________________    Example  Plating bath composition (g/liter)    No.      Nickel sulfate                         Nickel chloride                                     Boric acid    ______________________________________    1        300         90          30    2        300         90          30    3        300         90          30    4        300         90          30    5        300         90          30    6        300         90          30    7        300         90          30    8        300         90          30    9        300         90          30    10       300         90          30    11       300         90          30    ______________________________________

                                      TABLE 4    __________________________________________________________________________    Treating conditions    Example         Plating bath                 Plating bath temperature                              Cathode current density    No.  pH      (°C.) (A/dm.sup.2)    __________________________________________________________________________    1    3.5     55           10    2    4       55           10    3    4.15    55           10    4    4.2     55           10    5    5.5     55           10    6    4       55           8    7    4       55           7    8    4       55           4    9    4       55           3.5    10   4       55           3    11   3       55           10    __________________________________________________________________________

Tables 5 and 6 show the crystal shape of the slide surface 4a, the grainsize of the Ni crystals, the content S of the oriented Ni crystals andthe hardness for the examples 1 to 11.

                                      TABLE 5    __________________________________________________________________________         Crystal shape                Grain  Content S of    Example         of slide                size   oriented Ni crystals (%)                                       Hardness    No.  surface                (μm)                       {111}                           {200}                               {220}                                   {311}                                       (Hv)    __________________________________________________________________________    1    QP*    about 2                       17.3                           5.1 2.6 75  200    2    QP*    about 2                       22.3                           9.7 3.2 64.8                                       205    3    QP*    about 2                       31.7                           12  5.4 50.9                                       224    4    QP*    about 2-                       33  16.1                               10.5                                   40.4                                       222         Very fine                about 0.5         grain    5    DQP*   about 1.5                       42.5                           20  7.2 27.3                                       442                (ridge-wise)    6    QP*    about 2-                       33.1                           14.1                               14.8                                   38  225         Very fine                about 0.5         grain    __________________________________________________________________________     QP* = Quadrangular pyramid     DQP* = Deformed quadrangular pyramid

                                      TABLE 6    __________________________________________________________________________         Crystal shape                Grain  Content S of    Example         of slide                size   oriented Ni crystals (%)                                       Hardness    No.  surface                (μm)                       {111}                           {200}                               {220}                                   {311}                                       (Hv)    __________________________________________________________________________    7    QP*    about 2-                       31.6                           12.3                               19.8                                   36.3                                       248         Very fine                about 0.5         grain    8    QP*    about 2-                       29  10.2                               25.2                                   35.6                                       221         Very fine                about 0.5         grain    9    IQP*   about 2                       26  11  32.6                                   30.4                                       250    10   IQP*   about 3                       18.2                           11.5                               50.3                                   20  300    11   QP*    about 2                       17  3   0   80  210    __________________________________________________________________________     QP* = Quadrangular pyramid     IQP* = Imperfect quadrangular pyramid

The content S was determined in the following manner on the basis ofX-ray diffraction patterns (X-rays were applied in a directionperpendicular to the slide surface 4a) for the examples 1 to 11. Theexample 2 will be described below. FIG. 6 is an X-ray diffractionpattern for the example 2. The content S of each of the oriented Nicrystals was determined from each of the following expressions. Here,the term "{111} oriented Ni crystal" means, for example, an oriented Nicrystals with its {111} plane oriented toward the slide surface 4a.

{111} oriented Ni crystals: S₁₁₁ ={I₁₁₁ /IA₁₁₁)/T}×100

{200} oriented Ni crystals: S₂₀₀ ={(I₂₀₀ /IA₂₀₀)/T}×100

{220} oriented Ni crystals: S₂₂₀ ={(I₂₂₀ /IA₂₂₀)/T}×100

{311} oriented Ni crystals: S₃₁₁ ={(I₃₁₁ /IA₃₁₁)/T}×100

wherein each of I₁₁₁, I₂₀₀, I₂₂₀ and I₃₁₁ is a measurement (cps) of theintensity of X-rays reflected from each crystal plane; each of IA₁₁₁,IA₂₀₀, IA₂₂₀ and IA₃₁₁ is an intensity ratio of X-rays reflected fromeach crystal plane in an ASTM card. Further, IA₁₁₁ =100, IA₂₀₀ =42,IA₂₂₀ =21, and IA₃₁₁ =20. Furthermore, T=(I₁₁₁ /IA₁₁₁)+(I₂₀₀/IA₂₀₀)+(I₂₂₀ /IA₂₂₀)+(I₃₁₁ /IA₃₁₁).

FIG. 7 is a photomicrograph showing the crystal structure of the slidesurface 4a in the example 2. In FIG. 7, a large number of mutuallybitten quadrangular pyramid-shaped Ni crystals are observed. As shown inTable 5 and FIG. 6, the content S of the (hh0), i.e., {220} oriented Nicrystals in the example 2 is equal to 3.2%.

FIG. 8 is an X-ray diffraction pattern for the example 5. FIGS. 9A and9B are photomicrographs showing the crystal structure of the slidesurface 4a in the example 5. FIG. 9B is an enlarged photomicrographtaken from FIG. 9A. In FIGS. 9A and 9B, a large number of deformedquadrangular pyramid-shaped Ni crystals are observed. In this case, thecontent S of the {220} oriented Ni crystals is equal to 7.2%, as shownin Table 5 and FIG. 8.

A seizure test for the examples 1 to 11 was carried out in achip-on-disk manner to determine the relationship between the content Sof the {220} oriented Ni crystals and the seizure generating load,thereby providing the results shown in Table 7 and FIG. 10. Conditionsfor the test were as follows: the material of the disk was an Al-10% byweight of Si alloy; the rotational speed of the disk was 15 m/sec.; theamount of oil supplied was 0.3 ml/min.; and the area of the slidesurface of the chip made from the slide surface construction was 1 cm².

                  TABLE 7    ______________________________________    Example No. Seizure generating load (N)    ______________________________________    1           650    2           680    3           650    4           550    5           650    6           500    7           400    8           300    9           250    10          200    11          700    ______________________________________

FIG. 10 is a graph taken from Table 7, wherein points (1) to (11)correspond to the examples 1 to 11, respectively.

As apparent from Table 7 and FIG. 10, in the examples 1 to 7, which havea content S of the {220} oriented Ni crystals in a range of S<25%, theoil retention and initial conformability of the slide surface 4a areimproved. Hence, the seizure generating load is also significantlyenhanced, as compared with the examples 8, 9 and 10.

In the example 11, the content S of the {220} oriented Ni crystals isequal to 0%. By setting the content S at 0%, the quadrangularpyramid-shaped Ni crystals are precipitated in the largestconcentration, leading to the best seizure resistance.

In the metal crystals having the face-centered cubic structure, thecrystal shape in the slide surface, crystal planes located on the slantsand the like for the oriented metal crystals are shown in Table 8.

                                      TABLE 8    __________________________________________________________________________    Oriented          Crystal shape                  Crystal plane    metal on slide                  located on                          Characteristic of                                    Referential    crystal          surface slant   slant     drawing    __________________________________________________________________________    (3hhh)          Quadrangular                  (h00) plane:                          Good wettability                                    FIG. 11          pyramid highly atom-                          and good wear                  packed plane                          resistance    (h00) Quadrangular                  (hhh) plane:                          High hardness,                                    FIG. 12          pyramid close-packed                          excellent                  plane   wettability and                          good wear                          resistance    __________________________________________________________________________

It should be noted that for the wettability of the crystal planeslocated on the slants to oil or the like, the (hhh) plane is superior tothe (h00) plane.

The slide surface construction of the present invention is applicable,for example, to the slide portion of any of the following parts of aninternal combustion engine: pistons (land portions, skirt portions andring grooves), piston rings, piston pins, connecting rods, crankshafts,bearing metals, oil pump rotors, oil pump rotor housings, springs (endfaces), spring seats, spring retainers, cotters, rocker arms, rollerbearing outer cases, roller bearing inner cases, needle bearing outercases, needle bearing inner cases, valve stems, valve faces, hydraulictappets, water pump rotor shafts, pulleys, gears, transmission shaftportions, clutch plates, washers, bolts (bearing surfaces and threadedportions), chins, metal belts, cylinders, cam shaft bearings.

What is claimed is:
 1. A slide surface construction having a slidesurface, said slide surface construction comprising an aggregate ofmetal crystals, wherein:said metal crystals are formed from at least onemetal selected from the group consisting of Ni and Ni alloy, said metalcrystals have a face-centered cubic structure and are shaped at leastpartly into pyramid-shaped crystals, said aggregate of metal crystalsinclude (hh0) oriented crystals with their (hh0) planes (by Millerindices) oriented toward the slide surface, the content S of said (hh0)oriented crystals being in a range represented by 0%≦S<25%, and saidpyramid-shaped crystals include ones having their slant portions formedby (h00) planes.
 2. A slide surface construction according to claim 1,wherein said aggregate of metal crystals further includes (3hhh)oriented crystals with their (3hhh) planes (by Miller indices) orientedtoward the slide surface, said (3hhh) oriented crystals occupyinggreater than about 50% of said slide surface.
 3. A slide surfaceconstruction having a slide surface, said slide surface constructioncomprising an aggregate of crystals, wherein:said metal crystals areformed from at least one metal selected from the group consisting of Niand Ni alloy, said metal crystals have a face-centered cubic structureand are shaped at least partly into pyramid-shaped crystals, saidaggregate of metal crystals include (hh0) oriented crystals with their(hh0) planes (by Miller indices) oriented toward the slide surface, thecontent S of said (hh0) oriented crystals being in a range representedby 0%≦S<25%, and said pyramid-shaped crystals having slant portionswhich are formed by (hhh) planes.
 4. A slide surface constructionaccording to claim 3, wherein said aggregate of metal crystals furtherincludes (h00) oriented crystals with their (h00) planes (by Millerindices) oriented toward the slide surface, the content S of said (h00)oriented crystals being in a range represented by 3%≦S<20%.